As outlined in Chapter 3 of the USDA Inventory Methods document, tillage implements and timing are required for the Tier 3 method using DayCent. Users are strongly encouraged to enter a tillage system intensity for all crops where a planting and harvest date is specified. 


Tillage is categorized into full intensive tillage, reduced till, and no-till depending on the tillage implements and the number of passes. Tillage intensity is estimated for the planting period and the post-harvesting period. For the Tier 3 method, the intensities for each period are simulated with the model, using an intensity ranking from A to K (see Table 3-14 below). In COMET-Farm, these intensities are represented using values I through III. For example, Intensity H will appear in COMET-Farm as “Reduced Till (IV)”, and Intensity A will appear as “No Till (I).” 



If tillage implements are used during the Pre-Planting/Planting Season and/or Post-Harvest/ Harvest Season for the selected crop, please use the “Tillage Intensity Calculator” to populate the respective seasonal tillage system intensities. Per equation 3-13 in the USDA Inventory Methods document, the Tillage System Intensity Calculator will calculate the system intensity based on the mixing efficiency and tillage depth (cm) for all implements used. If users are unable to locate their exact implement from the list, please refer to Table 3-15 for each implement's respective mixing efficiency and tillage depth and select the closest implement.